The ultimate objective of the research projects in this application is to improve our understanding of, and our therapeutic options, in CLL through a coordinated investigation of the genetics, biochemistry, immunology and pharmacology of the disease and the associations between these biological parameters and clinical outcomes. Important to the success of this project is the collaboration with members of the Biostatistics Core, who will provide assistance in the design and analysis of the clinical and laboratory research projects, as well as assist in designing the further exploration of promising laboratory, genetic and demographic findings in the natural history database assembled through this Program Project. The purpose of the Biostatistics Core is to provide the following services that will be utilized by all the research projects. 1. To provide biostatistical collaboration for clinical research protocols, including all aspects of the design, conduct, analysis, and reporting of the clinical studies. 2. To provide biostatistical collaboration for all laboratory studies, including all aspects of the design, conduct, analysis, and reporting of such studies, as well as the correlation of laboratory results with clinical parameters and outcomes. 3. To provide all aspects of biostatistical assistance for exploratory and confirmatory studies using the natural history database. 4. To advice on database structure and assure easy flow of data out of the database for analysis. 5. To assist in the supervision of data management both at a central and a institutional level, in order to maintain and complete database. 6. To participate in the quality assurance programs of the CRC. 7. To work with the Consortium Director to develop guidelines and policies on data sharing and authorship, and assurance of the integrity of data used in publications. To participate in the internal scientific review of projects proposed suing the laboratory and clinical information contained in the database, as well as the tissue banking resources.